Faculté des sciences

Role of volatile chemostimuli in the sensory ecology of tsetse flies, Glossina spp., and host races of the larch bud moth, Zeiraphera diniana Guénée = : Rôle des composés volatils dans l'écologie sensorielle des mouches tsé-tsé, Glossina spp. et des deux races de la tordeuse grise du mélèze, Zeiraphera diniana Guénée

Syed, Zainulabeuddin ; Guérin, Patrick (Dir.)

Thèse de doctorat : Université de Neuchâtel, 2002 ; 1661.

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    In tsetse both sexes feed exclusively on the blood of vertebrates for a few minutes every 2–3 days. Tsetse flies seek cover from high temperatures to conserve energy and plants provide shelter for tsetse in all the biotopes they occupy. Recently, tsetse have taken cover in plantations and under the invasive bush Lantana camara that has invaded large areas of the tsetse fly belt of Africa. Flies from such refugia are implicated in sleeping sickness epidemics. In a wind tunnel we show that both foliage and an extract of volatiles from foliage of L. camara attract three tsetse spp. from different habitats: Glossina fuscipes fuscipes (riverine), G. brevipalpis (sylvatic) and G. pallidipes (savannah). Gas chromatography analysis of volatiles extracted from leaves and flowers of L. camara coupled to electroantennograme recordings show that 1-octen-3-ol and b-caryophyllene are the major chemostimuli for the antennal receptor cells of the three tsetse spp. studied. A binary mixture of these products attracted these flies in the wind tunnel. The gas chromatography linked electroantennograme analysis of the L. camara extracts also show that the antennal receptor cells of the three tsetse spp. respond similarly to groups of volatiles derived from the major biosynthetic and catabolic pathways of plants, i.e. to mono- and sesquiterpenes, to lipoxidation products and to aromatics. Mixtures of these plant volatiles also attracted tsetse in the wind tunnel. These findings show that tsetse flies have conserved a strong sensitivity to volatile secondary products of plants, underlining the fundamental role of vegetation in tsetse survival.